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Registers
1734
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Serial Bus 2.0 (USB) Controller
34.4.55 Transmit Endpoint FIFO Size (TXFIFOSZ)
describes dynamically setting endpoint FIFO sizes. The option of dynamically setting
endpoint FIFO sizes only applies to Endpoints 1-4. The Endpoint 0 FIFO has a fixed size (64 bytes) and a
fixed location (start address 0). It is the responsibility of the firmware to ensure that all the Tx and Rx
endpoints that are active in the current USB configuration have a block of RAM assigned exclusively to
that endpoint. The RAM must be at least as large as the maximum packet size set for that endpoint.
The transmit endpoint FIFO size (TXFIFOSZ) is shown in
and described in
Figure 34-81. Transmit Endpoint FIFO Size (TXFIFOSZ)
7
5
4
3
0
Reserved
DPB
SZ
R-0
R/W-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 34-85. Transmit Endpoint FIFO Size (TXFIFOSZ) Field Descriptions
Bit
Field
Value
Description
7-5
Reserved
0
Reserved
4
DPB
Double packet buffering enable
0
Single packet buffering is supported
1
Double packet buffering is enabled
3-0
SZ
0-Fh
Maximum packet size to be allowed (before any splitting within the FIFO of Bulk packets prior to
transmission). If m = SZ, the FIFO size is calculated as 2
(m+3)
for single packet buffering and 2
(m+4)
for
dual packet buffering.
34.4.56 Receive Endpoint FIFO Size (RXFIFOSZ)
describes dynamically setting endpoint FIFO sizes. The option of dynamically setting
endpoint FIFO sizes only applies to Endpoints 1-4. The Endpoint 0 FIFO has a fixed size (64 bytes) and a
fixed location (start address 0). It is the responsibility of the firmware to ensure that all the Tx and Rx
endpoints that are active in the current USB configuration have a block of RAM assigned exclusively to
that endpoint. The RAM must be at least as large as the maximum packet size set for that endpoint.
The receive endpoint FIFO size (RXFIFOSZ) is shown in
and described in
.
Figure 34-82. Receive Endpoint FIFO Size (RXFIFOSZ)
7
5
4
3
0
Reserved
DPB
SZ
R-0
R/W-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 34-86. Receive Endpoint FIFO Size (RXFIFOSZ) Field Descriptions
Bit
Field
Value
Description
7-5
Reserved
0
Reserved
4
DPB
Double packet buffering enable
0
Single packet buffering is supported
1
Double packet buffering is enabled
3-0
SZ
0-Fh
Maximum packet size to be allowed (before any splitting within the FIFO of Bulk packets prior to
transmission). If m = SZ, the FIFO size is calculated as 2
(m+3)
for single packet buffering and 2
(m+4)
for
dual packet buffering.